The present invention is related to a stripping composition for paints, varnishes or lacquers covering a substrate.
Strippers for paints and varnishes or lacquers are employed in two ways: by deposition or by immersion. The strippers applied by deposition are generally applied by brushing or spraying. They virtually always contain a thickener and are employed at ambient temperature (20.degree. C.). They are employed for small tasks or for objects to be stripped which cannot be immersed. This category includes stripping by the general public, professional stripping in the building trade and aeronautic stripping. The strippers by immersion employ either cold baths (often based on methylene chloride) or hot baths (often based on caustic soda). They are employed above all for stripping a large number of small articles (industrial stripping).
A stripping composition including, by volume, from 1 to 20% of a polar aprotic solvent such as dimethyl sulphoxide (DMSO) or N-methylpyrrolidinone (NMP) and from 99 to 80% of an ether such as tetrahydrofuran is already known from EP 0 490 726.
A stripping composition including, by volume, from 1 to 20% of a polar aprotic solvent like DMSO and NMP and from 99 to 80% of an ether exhibiting a flash point higher than 0.degree. C., a molar volume smaller than 160 and a molecule provided with one or more methoxy groups is already known from EP 0573 339. This ether may be especially anisole.
Although highly effective in their stripping action, these two above stripping compositions nevertheless have the disadvantage of being costly.
Furthermore, WO 93/07227 discloses the addition of water to solvents or mixtures of solvents considered to be effective in paint stripping. This document describes compositions containing 1) at least one organic solvent chosen from ethyl acetate, methyl ethyl ketone and toluene, 2) water, 3) at least one thickener and 4) at least one surfactant.
The effectiveness of these compositions is simply proportional to the quantity of organic solvent which is employed and, in any case, inferior to the effectiveness of the pure solvent.
In the stripper industry there is thus a need to find other compositions which are lower in cost but which are at least as effective as the compositions of the prior art.